The preparation, characterization, and reactions of mono- and di-1,3-benzoxazines are well documented in the literature. W. J. Burke (Journal of American Chemical Society, February 1949, Vol. 71, page 609) describes the reaction of p-substituted phenols with N,N-dimethylolamines to yield mono-1,3-benzoxazines. Burke et al (Journal of Organic Chemistry, October 1965, Vol. 30, page 3423) describe a "new aminoalkylation reaction"--the condensation of phenols with dihydro-1,3-aroxazines (another name for the present 1,3-benzoxazines). Schreiber (Ger. Offen. 2,255,504 and 2,323,936) describes the polymerization of benzoxazines in the preparation of phenolic resins with improved thermal, mechanical, and dielectric properties. ICI (694,489 GB) describes the preparation of mono-benzoxazines. G. Reiss et all (ACS polymer Preprints, Vol. 25, No. 2, August 1984, page 41) discuss the reactivities, polymerization, and application possibilities of benzoxazine, not including electrodeposition.
Higginbottom describes 2-component compositions in which primary and secondary amine functional resins are cured by added amine-free poly(dihydrobenzoxazines) for solvent-based surface coatings (U.S. Pat. No. 4,501,864) and as aqueous dispersions for electrocoat application (U.S. Pat. No. 4,507,428). Two disadvantages of the compositions described in the latter patent are that (1) the blended resin feed and tank stabilities are inadequate for most electrocoat applications, and (2) high oxazine content systems have poor solubility at the solids contents and pH strengths normally present in electrocoat tanks. These problems are overcome by the self-curable resins of the instant invention obtained by condensing a multifunctional benzoxazine with an amine or polyamine prior to coating application.